CLAUDE: guard JCuda GPUTileProcessor init behind the JNA backend flag

The RT/CUAS path runs on the JNA native backend (libtileproc.so, offline
nvcc 12.8); the legacy JCuda GPUTileProcessor is not needed there and its
NVRTC+cuLinkAddData dies on Blackwell/sm_120 (jcuda 12.6 emits compute_120
PTX the driver JIT rejects -> CUDA_ERROR_INVALID_PTX; no jcuda 12.8 exists).
- New maybeBuildGpuTileProcessor(): returns null (one-shot console note) when
  -Dtp.backend=jna, else builds GPUTileProcessor exactly as before. GpuQuad.
  create()/createRectilinear() already ignore a null gpuTileProcessor in JNA
  mode, and every GPU_TILE_PROCESSOR use is null-guarded or JCuda-only
  (ComboMatch orthomosaic already refuses JNA mode explicitly).
- All 19  sites in
  Eyesis_Correction now call the guard.
GUARD, not removal: jcuda mode (default, and the FOPEN/oracle path on its own
branch) is byte-for-byte unchanged, so JCuda stays available as the FOPEN
JCuda->JNA migration oracle. RT runs (-Dtp.backend=jna) no longer touch JCuda
-> no INVALID_PTX regardless of menu path. mvn package + test PASS.
Co-authored-by: Claude Opus 4.8 <claude-opus-4-8@anthropic.com>
Co-authored-by: Claude Fable 5 <claude-fable-5@anthropic.com>